Such a control module arrangement or compressed air maintenance unit is known, for example, from EP 1 400 702 A2. In the known compressed air maintenance unit, there is an internal bus through which maintenance modules or a control module for controlling the compressed air maintenance unit as well as other valve modules of the maintenance unit communicate. Input/output modules, SPS modules, or the like can also be connected to the bus system. The known control module arrangement is used for local diagnosis of the maintenance unit or the valve modules, which are added to the maintenance modules like a battery. Parts of the maintenance modules and/or the valves of the valve arrangement have sensors or diagnostic means, especially pressure sensors, whose sensor signals are transmitted via the internal bus to the control module. The control module has a field bus interface, by means of which an access to diagnostics on the part of an external control center is possible, which is used for controlling and monitoring the compressed air maintenance unit as well as the valves connected to this unit.
However, the diagnostic capabilities of the known compressed air maintenance unit are limited to the compressed air maintenance unit itself.